rtc-tx4939: fix races around device registration

* Use its own spinlock instead of rtc->irq_lock
* Check pdata->rtc before calling rtc_update_irq
* Disable interrupt after rtc_device_unregister

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 26 insertions, 25 deletions

diff --git a/drivers/rtc/rtc-tx4939.c b/drivers/rtc/rtc-tx4939.c
index 4a6ed1104fbb..9ee81d8aa7c0 100644
--- a/drivers/rtc/rtc-tx4939.c
+++ b/drivers/rtc/rtc-tx4939.c
@@ -17,6 +17,7 @@
 struct tx4939rtc_plat_data {
         struct rtc_device *rtc;
         struct tx4939_rtc_reg __iomem *rtcreg;
+        spinlock_t lock;
 };
 
 static struct tx4939rtc_plat_data *get_tx4939rtc_plat_data(struct device *dev)
@@ -52,14 +53,14 @@ static int tx4939_rtc_set_mmss(struct device *dev, unsigned long secs)
         buf[3] = secs >> 8;
         buf[4] = secs >> 16;
         buf[5] = secs >> 24;
-        spin_lock_irq(&pdata->rtc->irq_lock);
+        spin_lock_irq(&pdata->lock);
         __raw_writel(0, &rtcreg->adr);
         for (i = 0; i < 6; i++)
                 __raw_writel(buf[i], &rtcreg->dat);
         ret = tx4939_rtc_cmd(rtcreg,
                              TX4939_RTCCTL_COMMAND_SETTIME |
                              (__raw_readl(&rtcreg->ctl) & TX4939_RTCCTL_ALME));
-        spin_unlock_irq(&pdata->rtc->irq_lock);
+        spin_unlock_irq(&pdata->lock);
         return ret;
 }
 
@@ -71,18 +72,18 @@ static int tx4939_rtc_read_time(struct device *dev, struct rtc_time *tm)
         unsigned long sec;
         unsigned char buf[6];
 
-        spin_lock_irq(&pdata->rtc->irq_lock);
+        spin_lock_irq(&pdata->lock);
         ret = tx4939_rtc_cmd(rtcreg,
                              TX4939_RTCCTL_COMMAND_GETTIME |
                              (__raw_readl(&rtcreg->ctl) & TX4939_RTCCTL_ALME));
         if (ret) {
-                spin_unlock_irq(&pdata->rtc->irq_lock);
+                spin_unlock_irq(&pdata->lock);
                 return ret;
         }
         __raw_writel(2, &rtcreg->adr);
         for (i = 2; i < 6; i++)
                 buf[i] = __raw_readl(&rtcreg->dat);
-        spin_unlock_irq(&pdata->rtc->irq_lock);
+        spin_unlock_irq(&pdata->lock);
         sec = (buf[5] << 24) | (buf[4] << 16) | (buf[3] << 8) | buf[2];
         rtc_time_to_tm(sec, tm);
         return rtc_valid_tm(tm);
@@ -110,13 +111,13 @@ static int tx4939_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
         buf[3] = sec >> 8;
         buf[4] = sec >> 16;
         buf[5] = sec >> 24;
-        spin_lock_irq(&pdata->rtc->irq_lock);
+        spin_lock_irq(&pdata->lock);
         __raw_writel(0, &rtcreg->adr);
         for (i = 0; i < 6; i++)
                 __raw_writel(buf[i], &rtcreg->dat);
         ret = tx4939_rtc_cmd(rtcreg, TX4939_RTCCTL_COMMAND_SETALARM |
                              (alrm->enabled ? TX4939_RTCCTL_ALME : 0));
-        spin_unlock_irq(&pdata->rtc->irq_lock);
+        spin_unlock_irq(&pdata->lock);
         return ret;
 }
 
@@ -129,12 +130,12 @@ static int tx4939_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
         unsigned char buf[6];
         u32 ctl;
 
-        spin_lock_irq(&pdata->rtc->irq_lock);
+        spin_lock_irq(&pdata->lock);
         ret = tx4939_rtc_cmd(rtcreg,
                              TX4939_RTCCTL_COMMAND_GETALARM |
                              (__raw_readl(&rtcreg->ctl) & TX4939_RTCCTL_ALME));
         if (ret) {
-                spin_unlock_irq(&pdata->rtc->irq_lock);
+                spin_unlock_irq(&pdata->lock);
                 return ret;
         }
         __raw_writel(2, &rtcreg->adr);
@@ -143,7 +144,7 @@ static int tx4939_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
         ctl = __raw_readl(&rtcreg->ctl);
         alrm->enabled = (ctl & TX4939_RTCCTL_ALME) ? 1 : 0;
         alrm->pending = (ctl & TX4939_RTCCTL_ALMD) ? 1 : 0;
-        spin_unlock_irq(&pdata->rtc->irq_lock);
+        spin_unlock_irq(&pdata->lock);
         sec = (buf[5] << 24) | (buf[4] << 16) | (buf[3] << 8) | buf[2];
         rtc_time_to_tm(sec, &alrm->time);
         return rtc_valid_tm(&alrm->time);
@@ -153,11 +154,11 @@ static int tx4939_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
         struct tx4939rtc_plat_data *pdata = get_tx4939rtc_plat_data(dev);
 
-        spin_lock_irq(&pdata->rtc->irq_lock);
+        spin_lock_irq(&pdata->lock);
         tx4939_rtc_cmd(pdata->rtcreg,
                        TX4939_RTCCTL_COMMAND_NOP |
                        (enabled ? TX4939_RTCCTL_ALME : 0));
-        spin_unlock_irq(&pdata->rtc->irq_lock);
+        spin_unlock_irq(&pdata->lock);
         return 0;
 }
 
@@ -167,13 +168,14 @@ static irqreturn_t tx4939_rtc_interrupt(int irq, void *dev_id)
         struct tx4939_rtc_reg __iomem *rtcreg = pdata->rtcreg;
         unsigned long events = RTC_IRQF;
 
-        spin_lock(&pdata->rtc->irq_lock);
+        spin_lock(&pdata->lock);
         if (__raw_readl(&rtcreg->ctl) & TX4939_RTCCTL_ALMD) {
                 events |= RTC_AF;
                 tx4939_rtc_cmd(rtcreg, TX4939_RTCCTL_COMMAND_NOP);
         }
-        spin_unlock(&pdata->rtc->irq_lock);
-        rtc_update_irq(pdata->rtc, 1, events);
+        spin_unlock(&pdata->lock);
+        if (likely(pdata->rtc))
+                rtc_update_irq(pdata->rtc, 1, events);
         return IRQ_HANDLED;
 }
 
@@ -194,13 +196,13 @@ static ssize_t tx4939_rtc_nvram_read(struct kobject *kobj,
         struct tx4939_rtc_reg __iomem *rtcreg = pdata->rtcreg;
         ssize_t count;
 
-        spin_lock_irq(&pdata->rtc->irq_lock);
+        spin_lock_irq(&pdata->lock);
         for (count = 0; size > 0 && pos < TX4939_RTC_REG_RAMSIZE;
              count++, size--) {
                 __raw_writel(pos++, &rtcreg->adr);
                 *buf++ = __raw_readl(&rtcreg->dat);
         }
-        spin_unlock_irq(&pdata->rtc->irq_lock);
+        spin_unlock_irq(&pdata->lock);
         return count;
 }
 
@@ -213,13 +215,13 @@ static ssize_t tx4939_rtc_nvram_write(struct kobject *kobj,
         struct tx4939_rtc_reg __iomem *rtcreg = pdata->rtcreg;
         ssize_t count;
 
-        spin_lock_irq(&pdata->rtc->irq_lock);
+        spin_lock_irq(&pdata->lock);
         for (count = 0; size > 0 && pos < TX4939_RTC_REG_RAMSIZE;
              count++, size--) {
                 __raw_writel(pos++, &rtcreg->adr);
                 __raw_writel(*buf++, &rtcreg->dat);
         }
-        spin_unlock_irq(&pdata->rtc->irq_lock);
+        spin_unlock_irq(&pdata->lock);
         return count;
 }
 
@@ -259,6 +261,7 @@ static int __init tx4939_rtc_probe(struct platform_device *pdev)
         if (!pdata->rtcreg)
                 return -EBUSY;
 
+        spin_lock_init(&pdata->lock);
         tx4939_rtc_cmd(pdata->rtcreg, TX4939_RTCCTL_COMMAND_NOP);
         if (devm_request_irq(&pdev->dev, irq, tx4939_rtc_interrupt,
                              IRQF_DISABLED, pdev->name, &pdev->dev) < 0)
@@ -277,14 +280,12 @@ static int __init tx4939_rtc_probe(struct platform_device *pdev)
 static int __exit tx4939_rtc_remove(struct platform_device *pdev)
 {
         struct tx4939rtc_plat_data *pdata = platform_get_drvdata(pdev);
-        struct rtc_device *rtc = pdata->rtc;
 
-        spin_lock_irq(&rtc->irq_lock);
-        tx4939_rtc_cmd(pdata->rtcreg, TX4939_RTCCTL_COMMAND_NOP);
-        spin_unlock_irq(&rtc->irq_lock);
         sysfs_remove_bin_file(&pdev->dev.kobj, &tx4939_rtc_nvram_attr);
-        rtc_device_unregister(rtc);
-        platform_set_drvdata(pdev, NULL);
+        rtc_device_unregister(pdata->rtc);
+        spin_lock_irq(&pdata->lock);
+        tx4939_rtc_cmd(pdata->rtcreg, TX4939_RTCCTL_COMMAND_NOP);
+        spin_unlock_irq(&pdata->lock);
         return 0;
 }